Andesanthus

''Andesanthus'' is a genus of flowering plant in the family Melastomataceae, native to Colombia, Costa Rica, Ecuador, Panama, Peru and Venezuela. The genus was established in 2019 for some species formerly placed in '' Tibouchina''. Some species are cultivated as ornamental shrubs or trees.

Description

Species of ''Andesanthus'' are trees between 5 and 20 m tall at maturity or shrubs 1–3 m tall. Their leaves are opposite and petiolate (stalked). The inflorescence is a terminal panicle or some modification of a panicle. The flowers are perigynous wih a bell- or urn-shaped hypanthium, externally with many soft hairs (pubescent) in most species. The flowers have five free petals, which are pink, purple, magenta or white in colour, or initially magenta or rose-red fading to lavender with age. Flowers have ten stamens, either all the same size or in two distinct sizes. The connective at the base of the anther of the stamen is prolonged and modified into a bilobed ventral appendage. The numerous seeds are shaped like a spiral (cochleate) which may be elongated.

''Andesanthus'' can be distinguished by its coating of small flattened scales (lepidote), hairless (glabrous) stamens which either have all their anthers yellow if of one size or have the larger anthers yellow and the smaller anthers pink or red if of two sizes.

Taxonomy

The genus ''Andesanthus'' was erected in 2019. The name reflects the fact that the majority of species occur in the Andes.

In 1885, in his treatment for ''Flora brasiliensis'', Alfred Cogniaux used a broad concept of the genus '' Tibouchina'', transferring into it species at that time placed in many other genera. This broad concept was generally adopted subsequently, and around 470 taxa were at one time or another assigned to ''Tibouchina'', including those placed in ''Andesanthus'' in 2019. A phylogenetic analysis in 2013 based on molecular data (2 plastid and 1 nuclear regions) showed that the traditional circumscription of ''Tibouchina'' was paraphyletic. Four major clades were resolved within the genus, which were supported by morphological, molecular and geographic evidence. A further molecular phylogenetic study in 2019 used the same molecular markers but included more species. It reached the same conclusion: the original broadly circumscribed ''Tibouchina'' consisted of four monophyletic clades. The authors proposed a split into four genera: a more narrowly circumscribed ''Tibouchina'', two re-established genera ''Pleroma'' and '' Chaetogastra'', and a new genus, ''Andesanthus''. The part of their maximum likelihood cladogram which includes former ''Tibouchina'' species is as follows, using their genus names and with shading added to show the original broadly circumscribed ''Tibouchina'' s.l. (The relationship between ''Chaetogastra'' and the genus '' Brachyotum'' differed between analyses.)

''Andesanthus'' is shown to be sister to either ''Chaetogastra'' or a clade combining ''Chaetogastra'' and ''Brachyotum''.

Species

, Plants of the World Online accepted the following species:
*'' Andesanthus aristeguietae'' (Wurdack) P.J.F.Guim. & Michelang.
*'' Andesanthus elegantulus'' (Todzia & Almeda) P.J.F.Guim. & Michelang.
*'' Andesanthus gleasonianus'' (Wurdack) P.J.F.Guim. & Michelang.
*'' Andesanthus inopinatus'' (Wurdack) P.J.F.Guim. & Michelang.
*'' Andesanthus lepidotus'' (Humb. & Bonpl.) P.J.F.Guim. & Michelang.
*'' Andesanthus narinoensis'' (Wurdack) P.J.F.Guim. & Michelang.
*'' Andesanthus paleaceus'' (Triana) P.J.F.Guim. & Michelang.
*'' Andesanthus silvestris'' (Todzia & Almeda) P.J.F.Guim. & Michelang.
*'' Andesanthus wurdackii'' (Almeda & Todzia) P.J.F.Guim. & Michelang.

Distribution and habitat

''Andesanthus'' species are found in Central America ( Costa Rica and Panama) and northern South America ( Colombia, Ecuador, Peru and Venezuela). Most are found in the Andes. Two species are found in the mountains of Costa Rica and Panama. The largest number of species are found in Colombia. They grow in cool montane forests and along forest margins.

Cultivation

Some species of ''Andesanthus'' are cultivated as ornamental shrubs or trees. The cultivar 'Alstonville' of ''Andesanthus lepidotus'' ( syn. ''Tibouchina lepidota'') was developed in Alstonville, New South Wales in Australia, where this species and its cultivars are popular cultivated plants.

References

{{Taxonbar, from=Q93745904

Melastomataceae
Melastomataceae genera